Creating unit tests without relying on a testing framework: A guide

Question

Creating unit tests without relying on a testing framework: A guide

My goal is to unit test a simple function using pure JavaScript:

NS.isType = function (type, obj) {
    if (obj.constructor && obj.constructor.name) {
        return obj.constructor.name === type;
    }
    return toString.call(obj) === '[object ' + type + ']';
};

I am eager to start practicing unit testing in JavaScript without relying on any framework. I want to grasp the concept through a hands-on example before delving into more comprehensive resources like the O'Reilly book, (2013), which covers unit testing with frameworks.

Could someone guide me on how to unit test the above method using only pure JavaScript without any external library?

javascript testing

Answer 1

Answer №1

Unit testing is like a game of red light green light.

First, you create a test outlining the expected behavior of your function. Running the test will result in failure since the function has not been implemented yet (RED).

Next, you implement the function and run the test again. This time, the test will pass as the function now behaves correctly (GREEN).

To ensure the effectiveness of your test, make slight changes to cause it to fail once more (to confirm it doesn't always pass) (RED).

Adjust the test so that it passes once again.

During unit testing, asserting plays a crucial role. Here's a simple example:

function addNumbers(A, B){
  return A + B;
}
//test suite snippet:
var tests=[];
function assertEqual(a, b, message){
  tests.push({
    pass: a === b,
    message: message
  });
}
assertEqual(addNumbers(1,2), 3, "Ensuring 1 plus 2 equals 3");
assertThrows(addNumbers("hello",7), "Passing a string as one of the parameters should trigger an error");

Answer 2

Unit testing is like a game of red light green light.

First, you create a test outlining the expected behavior of your function. Running the test will result in failure since the function has not been implemented yet (RED).

Next, you implement the function and run the test again. This time, the test will pass as the function now behaves correctly (GREEN).

To ensure the effectiveness of your test, make slight changes to cause it to fail once more (to confirm it doesn't always pass) (RED).

Adjust the test so that it passes once again.

During unit testing, asserting plays a crucial role. Here's a simple example:

function addNumbers(A, B){
  return A + B;
}
//test suite snippet:
var tests=[];
function assertEqual(a, b, message){
  tests.push({
    pass: a === b,
    message: message
  });
}
assertEqual(addNumbers(1,2), 3, "Ensuring 1 plus 2 equals 3");
assertThrows(addNumbers("hello",7), "Passing a string as one of the parameters should trigger an error");

Creating unit tests without relying on a testing framework: A guide

Answer №1

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